Parkinson’s First Law is that work expands to fill the time available,
but Parkinson never said whose time.
As I’ve watched several organizations I’m involved in mature,
I’ve realized that the people who run them think in terms of their time,
rather than the volunteers’.
I certainly did this when I was running Software Carpentry:
it was my main focus,
so the volume of lessons and email I (unconsciously) expected people to read was scaled to a full-time job,
rather than to a couple of hours once a month.

I’d therefore like to propose that volunteer organization of any significant size or age
should set themselves a budget for how much attention they require from their members,
just like they set themselves a budget for their expenditures.
The factors I think most important in that budget are:

the size of the teams that most volunteers work in (i.e., what they need to know for everyday operations),

the total size of the organization (i.e., overall governance), and

the organization’s age (because special cases accumulate with experience).

I think the number of pages of rules should grow logarithmically with each factor,
so that (for example) doubling the size of the organization only adds one more page to the required reading.
Add in a constant factor for necessary onboarding,
and Wilson’s Totally Made-Up Formula is:

pages = 4 + ⸢log2(team size)⸣ + ⸢log2(org size)⸣ + ⸢log2(org age)⸣

where ⸢x⸣ rounds up to the next integer. As a quick guide to what this looks like:

If you’re working on your own (team size 1, org size 1) in your first year, you’re allowed 4 pages of rules.

If people work in pairs in a 10-person organization that’s 3 or 4 years old, you’re allowed 10 pages of rules.

If people work in teams of 10 in a 1000-person organization that’s a decade old, you’re allowed 21 pages of rules.

Feel free to make up your own formula,
but please don’t put things in appendices or say that they’re “recommended but not required”:
adopting a budget only to immediately go around it is a waste of everyone’s time and energy.
The point is,
every time you want to add more rules
you should look at the ones you have and cut some
so that the overall load on your volunteers grows very slowly.
It will force you to think clearly and frequently about what your organization’s actual priorities are,
and your volunteers will be grateful that you took the time to think things through from their point of view.